V-CaHAp as a recyclable catalyst for the green multicomponent synthesis of benzochromenes

A simple and efficient one-pot method has been developed for the synthesis of benzochromenes (4a–k) using V-CaHAp as a heterogeneous catalyst by the condensation of aldehydes, β-naphthol and malononitrile in ethanol as solvent at room temperature for 20 min. The reaction, with this catalyst was carried out under mild reaction conditions with very good to excellent yields (89–98%). The material can be recycled very easily and reused for at least 6 runs without substantial loss in activity, which makes this methodology environmentally benign. We achieved a feasible and cost-effective synthesis by using non-toxic materials and minimal catalyst which is easy to handle.